Iron binding to human lactoferrin alters reactivity of the protein with plant lectins

Binding of Fe by human apolactoferrin results in altered reactivity of the glycoprotein with plant lectins. Reaction with wheat germ agglutinin (WGA) and peanut agglutinin (PNA) was abolished with Fe binding. Reaction with the lectins from Datura stramonium (DSA) and Aleuria aurantia (AAA) was significantly reduced but not fully abolished on Fe binding, while reaction with the Artocarpus integrifolia lectin (Jacalin) and Sambucus nigrabark (SNA) was not changed at all. Loss of WGA reactivity occurred when only one of two Fe binding sites on the molecule was saturated. The results demonstrate conformational changes that are associated with high-avidity binding of Fe by lactoferrin.